[Dovecot] migrate 15K users to new domain name

[Jan-Frode Myklebust]

I need to migrate 15K users to a new domain name, and plan to use "dsync
mirror" in the transition phase. Could someone confirm that this should
work:

Before giving users access to new-domain do a first sync to get all the
stale data over:

	for user in $old-domain; do
		dsync mirror $user at old-domain $user at new-domain
	done

Configure sieve vacation filter to forward all messages from
$user at old-domain to $user at new-domain, and notify sender of changed
address.

Give users access to both new-domain and old-domain, and do a final
sync.

	for user in $old-domain; do
		dsync mirror $user at old-domain $user at new-domain
		dsync mirror $user at old-domain $user at new-domain  # twice in case the first was slow 
		drop all messages for $user at old-domain
		Leave notice message for $user at old-domain saying he should use new-domain
	done

Wait a few weeks/months, and then drop all users at old-domain.


Does this look sensible? 


  -jf